diff --git a/src/Lib.hs b/src/Lib.hs
index 9090bcd0031fdf3053c44de95c8f2f96cf0d6638..996cf19fed21a038cca8cbcb950b286944880907 100644
--- a/src/Lib.hs
+++ b/src/Lib.hs
@@ -22,7 +22,13 @@ import Game (
 import Minimax (isWin)
 
 header :: Value
-header = object ["Access-Control-Allow-Origin" .= ("https://pemfung-fun.netlify.app" :: String, "https://assignment1-law.ariqbasyar.id" :: String)]
+header = object [
+  "Access-Control-Allow-Origin" .= (
+    "https://pemfung-fun.netlify.app" :: String
+    , "https://assignment1-law.ariqbasyar.id" :: String
+    )
+  , "Content-Type" .= ("application/json" :: String)
+  ]
 
 handler :: Request -> Context () -> IO (Either String Response)
 handler Request {..} _ = do